Femoral Acetabular Impingement (FAI)

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What Is Femoral Acetabular Impingement (FAI)?

Your hip is a ball-and-socket joint. The ball is the head of the femur bone. The socket is the acetabulum of the pelvis.

The acetabulum has a ring of cartilage around it — called the labrum — that cushions the hip joint.

FAI occurs when a small area of the head of the femur has a deformity on it and the bones don't fit together properly.

When the bones rub together, it causes damage to the hip joint.

FAI causes

FAI happens when:

  • People are born with a hip deformity.
  • The bones don't develop normally in childhood.

If you're physically active, you may experience FAI symptoms earlier, but exercise doesn't cause the problem.

Types of FAI

There are three types of FAI, depending on the bone problem.

  1. Pincer impingement: When extra bone juts out over the socket of the hip joint.
  2. Cam impingement: When the ball is misshapen and isn't able to rotate in the socket.
  3. A combination of pincer and cam impingements.

If left untreated, FAI can tear the cartilage in the acetabulum (a labral tear).

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FAI Symptoms and Diagnosis

FAI symptoms

Symptoms of FAI mostly occur because of cartilage damage around the hip joint.

Since the hip joint is near the groin, pain often begins in that area.

FAI symptoms include:

  • Pain that starts in the groin and moves to the outside of the hip.
  • A dull ache in the hip or groin area.
  • A sharp, stabbing pain when you turn, twist, or squat.
  • Limping and joint stiffness.

FAI diagnosis

Your doctor will take your medical history and perform a physical exam.

He or she will push your knee up to your chest and rotate it inward. If this causes pain, it's likely you have an impingement.

Your doctor may order imaging tests to look for FAI and any bone deformity. These scans will also show any joint damage.

Tests you may have include:

  • X-ray
  • CT scan
  • MRI 

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Femoral Acetabular Impingement (FAI) Treatment

At first — after a diagnosis of FAI — you should stop activity and give your hip a chance to rest.

You can also take non-steroidal anti-inflammatory drugs (NSAIDs) for pain.

If the pain doesn't go away, you should seek treatment from a doctor. Without treatment, FAI can worsen and cause more damage to the hip joint.

Nonsurgical FAI treatment

Your doctor will often try nonsurgical treatments first, such as:

  • Rest
  • Avoiding activities that aggravate the hip
  • Injections
  • Physical therapy

Exercises focused on strengthening the muscles that support your hip joint can lower the stress on the damaged cartilage and help you heal.

Maintaining flexibility in the joint also helps reduce FAI symptoms.

FAI surgery

If therapy and rest don't ease your FAI symptoms, your doctor may suggest hip arthroscopy. UPMC surgeons are leaders in hip arthroscopy, pioneering the procedure and advancing our understanding of the field.

This minimally invasive surgery allows your doctor to repair the damaged part of the hipbone through small incisions. This FAI surgical treatment has a high success rate for reducing symptoms and preventing further joint damage.

Recovery from surgery involves several weeks of rest, followed by rehab to strengthen the joint. 

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